Systems have been developed that allow the fusion of protein-free, artificial vesicles to planar membranes. However, the detailed dynamics of the fusion process are not yet understood. In particular, a theoretical analysis indicates that the vesicle should incorporate itself into the middle of the membrane prior to the final fusion. In order to test this prediction, we are attempting to patch clamp large, unilamellar vesicles as they fuse to planar membranes. The membrane movements of the fusion process can then be tracked through capacitance measurements. In addition, the patch pipette allows the control of the intravesicle pressure and the detection of fusion pores as they arise. A similar experiment on smaller (~100 nm) vesicles will utilize voltage sensitive dyes and provide a control on the experimental protocol.